The idle mode is a working mode of a terminal in a mobile broadband Radio Access System (RAS). In the idle mode, a MSS can move in a set area, and receive the downlink broadcast service messages at regular intervals. The downlink broadcast service messages are designed to notify the MSS whether any downlink service needs to be transmitted. While roaming in an area, a MSS does not need to get registered on the Basestation (BS) of the cell where the MSS is roaming. Meanwhile, while roaming in different cells, the MSS does not need to perform normal operation processes, such as handover, which is conducive to saving MSS power and air interface resources.
Multiple BSs make up a group, called Paging Group (PG). A PG is intended to constitute a continuous area, inside which the MSS does not need to send uplink services but can use downlink paging channels to judge whether any downlink service is sent to the MSS. On one hand, a PG must be large enough to ensure that most MSSs are kept in the same PG in a long time; on the other hand, a PG must be small enough to ensure that the overhead spent by the PG for paging a MSS is reasonable.
In the normal operation process on a Serving BS (SBS), the MSS may request to enter the idle mode by sending a message. Likewise, a serving BS may require an MSS to enter the idle mode by sending a message. No matter whether the MSS requests to enter the idle mode through a message or the serving BS requires the MSS to enter the idle mode through a message, the MSS must finish deregistration and enter the idle mode within the specified time.
The Worldwide Interoperability for Microwave Access (WiMAX) standard currently under development defines a paging reference model in the idle mode, in which the Paging Controller (PC) is a network entity that controls the activities of a MSS in the idle mode. The PC is a logic entity in the current WiMAX network architecture. Since a PC needs to send paging messages according to the PG that currently contains the MSS, a Location Register (LR) is required for storing the state information, paging information and service flow information of the MSS. Generally, each LR logic entity corresponds to one PC logic entity, and the two logic entities work in the same physical Network Element (NE). PCs can be divided into the following two types: (i) anchor PC: each MSS in the idle mode uniquely corresponds to an anchor PC which controls the actions of the MSS in the idle mode and controls the relevant processes; (ii) relay PC: one idle MSS may have one or more relay PCs for communicating with the anchor PC. For different MSSs, a PC may act as both anchor PC and relay PC.
Generally, a Paging Agent (PA) located in a BS is designed to handle paging and the functions related to the idle mode.
Regardless of other physical Network Elements (NEs) and logic entities in the WiMAX network, the following description is made with respect to the WiMAX paging reference model shown in FIG. 1 (the technical solution under the present invention includes but is not limited to the application in a WiMAX system).
According to the paging reference model shown in FIG. 1, when a MSS requests to enter the idle mode on the SBS, or the SBS instructs the MSS to enter the idle mode, message interaction will be performed between the MSS and SBS and between the SBS and the back-end NE “ASN GW” to notify the PC that the MSS enters the idle mode (this is implemented in the Access Service Network Gateway (ASN GW)). The state information, paging information, and service flow information of the MSS are saved in the corresponding LR.
FIG. 2 shows the process of entering the idle mode initiated by a MSS. The detailed procedure is as follows:
(1) The MSS sends a deregistration request (DREG_REQ) to the PA/DPF (or
PA/SBS for the reason that DPF is located in the SBS);
(2)-(3) The local PC receives the DREG_REQ, specifies an anchor PC for the MSS, allocates paging parameters for the MSS to enter the idle mode, and then returns such information to the serving PA through a MSS Dreg Rsp message;
(4)-(5) The serving PA uses the functions of its Data Path Function (DPF) entity to send a data path release request (Data Path Rel Req) to the relay DPF on the MSS link, in order to release the link on the MSS. The relay DPF on the link forwards the Data Path Rel Req to the anchor DPF;
(6) The anchor DPF sends a MSS information request (MSS Info Req) message to the anchor PC specified in the Data Path Rel Req message;
(7) After receiving the MSS Info Req, the anchor PC contacts the anchor authenticator to verify whether to allow the MSS to enter the idle mode, and replies with a MSS Info Rsp to the anchor DPF;
(8) According to the MSS Info Rsp, the anchor DPF sends a Data Path Rel Rsp to the relay DPF if the MSS is allowed to enter the idle mode;
(9) The relay DPF sends a Data Path Rel Rsp message to the serving PA/DPF; and
(10) After receiving the Data Path Rel Rsp, the PA/DPF confirms that the MSS enters the idle mode successfully, and sends, from the air interface, a deregistration command (DREG_CMD) message to the MSS, thus finishing the process of entering the idle mode.
However, the inventor discovered that the prior art has defects about the process of entering the idle mode initiated by the network; the prior art does not specify the process of the MSS entering the idle mode initiated by the network, which impairs the stability of the process of entering the idle mode.
The invention also discovered that the prior art does not consider another circumstance of entering the idle mode initiated by the network: when the network initiates the process of entering the idle mode, the network cannot enable the MSS to enter the idle mode unless the MSS sends a request of entering the idle mode after a delay of REQ-duration. Moreover, when the network requires the MSS to enter the idle mode, the MSS may require a delay for its own reasons before entering the idle mode.